A conventional gas burner as used in a stove, for example, has a safety valve serving in a role of a safety device for continuing or stopping the gas supply by using electromotive force produced, or lost, with a thermocouple, and a governor for injecting combustion fuel gas into a mixing room via a venturi tube under an even pressure.
Herein, some gas is fed from a gas valve through a gas pressure control into a main burner, while the remaining gas is fed from a gas valve into the pilot burner without passing through the gas pressure control.
Gas fed into main burner should be at an even gas pressure, while gas fed into a pilot burner is at an uneven gas pressure. Thus, a lifting phenomenon occurs at the pilot burner due to the uneven gas pressure. When flaming resulting from the lifting phenomenon is detected by a thermocouple, the electromotive force of the thermocouple is lowered, or lost, to thereby force a safety device to interrupt the supply of gas into the main burner. This phenomenon causes a deterioration of the function for performing the original object of the safety device, namely the function of stopping the fuel supply during an oxygen shortage, whenever that may happen in the vicinity of a gas stove, and thus impairs the reliability of the safety device.
In a structure in which the gas supplied to a main burner nozzle is injected into the interior of main burner through a venturi tube, the centerline of the main burner nozzle and the centerline of the venturi tube are not placed in a coaxial line; consequently, the air volume supplied to the main burner is relatively lower.
These phenomena lead to another problem which brings about incomplete combustion with an improper mixing ratio of air-to-combustion fuel.